The 26-year-old actress admits a lot of discussion and planning went into what sort of pubic hair wig she would display in the film, because her character Lisbeth Salander is naked in so many scenes in the new thriller.

In an interview with the Metro.us, she revealed: "There was a lot of discussion that went into my merkin for the movie, because I was naked quite a lot. And I don't think a lot of people will notice all of the attention that went into that. But there were a lot of discussions around that."

One of the things the director David Fincher and the production crew wanted to get right was the colour of the intimate hair piece.

Rooney explained: "Well, you know, in the book she's meant to have strawberry-blonde hair originally and she dyes it, so we had a special merkin made that was, you know, strawberry-blonde so that it would fit."

The actress stars opposite Daniel Craig in the movie, which is based on the Swedish novel of the same name by Stieg Larsson.

There are two other books which make up the 'Millennium Series', 'The Girl Who Played with Fire' and 'The Girl Who Kicked the Hornets' Nest'.